1. Field of the Invention
A multilumen tubing, and more particularly, a tubing having a multilumen portion in fluid communication with a single lumen portion and having unitary construction.
2. Prior Art
A variety of multilumen catheters and similar tubing is well established in the prior art. Chee, et al., in U.S. Pat. No. 5,542,937, discloses a multilumen catheter made by an extrusion process wherein the lumens are coextensive with the length of the catheter. Means for changing the composition of the clastomer comprising the catheter body during the extruded elongation of the catheter is discussed.
Miller et al., in U.S. Pat. No. 5,683,640, discloses a dual lumen catheter wherein a first lumen is coextensive with the length of the catheter and a second lumen, parallel to the first lumen, is shorter than the first lumen and exits the catheter via a port in the catheter wall. A hollow hub is affixed to one end of the catheter and is in fluid communication with both the first and second lumen. Medical applications of the catheter include infusion of fluids and peritoneal dialysis.
Multilumen catheters, wherein one lumen is in fluid communication with a second lumen within the body of the catheter, are known in the art. For example, Willard et al., in U.S. Pat. No. 5,219,335, discloses an intravascular introducer sheath having two lumens. An axial lumen is coextensive with the body of the sheath and dimensioned to accommodate an introducer wire therewithin; the introducer wire being of the type commonly employed for inserting a catheter in a blood vessel. In this procedure, a wire is threaded through an excision in the skin and advanced through a blood vessel until the end of the wire is in a predetermined location within the vascular system. The distal end of the axial lumen of the introducer sheath is placed over the proximal (accessible) end of the wire and advanced along the wire until the introducer sheath is in position. The wire is then withdrawn and a suitable device, such as a stent disposed on the outer surface of a catheter, is advanced through the axial lumen of the introducer sheath until the device is correctly positioned within the blood vessel. The introducer sheath is then removed. After deployment of the device, the catheter may be removed.
The axial lumen in such introducer sheaths, through which the guidewire passes, is straight. This construction, (i.e., a straight axial lumen) permits facile passage of the introducer sheath over the guidewire. Willard et al.""s introducer sheath has a second lumen that is parallel to the axial lumen. A connection providing fluid communication between the second lumen and the axial lumen is disposed near the distal end of the introducer sheath. Inasmuch as the axial lumen is straight, the second lumen is bent at the interluminal connection rendering the juncture between the two lumens asymmetric. For the purpose of an introducer sheath, a catheter having a tubular body portion with a straight axial lumen and an asymmetric, abruptly bent second lumen is acceptable and perhaps even essential. For other applications, however, such as the use of a single to multilumen catheter for transporting fluids, the asymmetric abrupt bend in the transition portion comprised of the connection can produce unwanted turbulence at the juncture of two fluid streams. It is, therefore, desirable to provide a single to multilumen catheter wherein the transition portion forming the connection between the single lumen and multilumen portion of the catheter is both smooth and symmetric.
The attachment of a hub to a multilumen tubing, or any tubing, compromises the structural integrity of the assembly. Either axial or lateral tension on the hub may cause it to separate from the catheter. This problem can be overcome. by providing a multilumen catheter having unitary construction, wherein multiple lumens, terminating at one end of a catheter, are in fluid communication with a single lumen terminating at the opposing end of the catheter.
It is a first object of the invention to provide a unitary tubing having a multilumen end and a single lumen end wherein fluid communication between the single lumen and the multiple lumens is established by means of a transition portion disposed therebetween.
It is a further object of the invention to provide a unitary tubing meeting the above objectives and wherein the unitary tubing has a uniform outer diameter along the entire length thereof.
It is still another object of the present invention to provide a unitary tubing meeting the above objectives wherein the transition portion disposed between the single lumen and multiple lumen portions of the tubing is symmetric with respect to an axis defined by the direction defined by the single lumen.
It is another object of the invention to provide a medical catheter meeting the above-stated objective in any desired length and diameter.
It is still a further object of the invention to provide an apparatus and method for making a multilumen tubing meeting the objectives stated above.
The features of the invention believed to be novel arc set forth with particularity in the appended claims. However the invention itself, both as to organization and method of operation, together with further objects and advantages thereof may be best be understood by reference to the following description taken in conjunction with the accompanying drawings in which: